/*
 * Copyright 2002-2010 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.util;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Locale;
import java.util.Properties;
import java.util.Set;
import java.util.StringTokenizer;
import java.util.TreeSet;

/**
 * Miscellaneous {@link String} utility methods.
 *
 * <p>Mainly for internal use within the framework; consider
 * <a href="http://jakarta.apache.org/commons/lang/">Jakarta's Commons Lang</a>
 * for a more comprehensive suite of String utilities.
 *
 * <p>This class delivers some simple functionality that should really
 * be provided by the core Java <code>String</code> and {@link StringBuilder}
 * classes, such as the ability to {@link #replace} all occurrences of a given
 * substring in a target string. It also provides easy-to-use methods to convert
 * between delimited strings, such as CSV strings, and collections and arrays.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @author Keith Donald
 * @author Rob Harrop
 * @author Rick Evans
 * @author Arjen Poutsma
 * @since 16 April 2001
 * @see org.apache.commons.lang.StringUtils
 */
public abstract class StringUtils {

   private static final String FOLDER_SEPARATOR = "/";

   private static final String WINDOWS_FOLDER_SEPARATOR = "\\";

   private static final String TOP_PATH = "..";

   private static final String CURRENT_PATH = ".";

   private static final char EXTENSION_SEPARATOR = '.';


   //---------------------------------------------------------------------
   // General convenience methods for working with Strings
   //---------------------------------------------------------------------

   /**
    * Check that the given CharSequence is neither <code>null</code> nor of length 0.
    * Note: Will return <code>true</code> for a CharSequence that purely consists of whitespace.
    * <p><pre>
    * StringUtils.hasLength(null) = false
    * StringUtils.hasLength("") = false
    * StringUtils.hasLength(" ") = true
    * StringUtils.hasLength("Hello") = true
    * </pre>
    * @param str the CharSequence to check (may be <code>null</code>)
    * @return <code>true</code> if the CharSequence is not null and has length
    * @see #hasText(String)
    */
   public static boolean hasLength(CharSequence str) {
      return (str != null && str.length() > 0);
   }

   /**
    * Check that the given String is neither <code>null</code> nor of length 0.
    * Note: Will return <code>true</code> for a String that purely consists of whitespace.
    * @param str the String to check (may be <code>null</code>)
    * @return <code>true</code> if the String is not null and has length
    * @see #hasLength(CharSequence)
    */
   public static boolean hasLength(String str) {
      return hasLength((CharSequence) str);
   }

   /**
    * Check whether the given CharSequence has actual text.
    * More specifically, returns <code>true</code> if the string not <code>null</code>,
    * its length is greater than 0, and it contains at least one non-whitespace character.
    * <p><pre>
    * StringUtils.hasText(null) = false
    * StringUtils.hasText("") = false
    * StringUtils.hasText(" ") = false
    * StringUtils.hasText("12345") = true
    * StringUtils.hasText(" 12345 ") = true
    * </pre>
    * @param str the CharSequence to check (may be <code>null</code>)
    * @return <code>true</code> if the CharSequence is not <code>null</code>,
    * its length is greater than 0, and it does not contain whitespace only
    * @see java.lang.Character#isWhitespace
    */
   public static boolean hasText(CharSequence str) {
      if (!hasLength(str)) {
         return false;
      }
      int strLen = str.length();
      for (int i = 0; i < strLen; i++) {
         if (!Character.isWhitespace(str.charAt(i))) {
            return true;
         }
      }
      return false;
   }

   /**
    * Check whether the given String has actual text.
    * More specifically, returns <code>true</code> if the string not <code>null</code>,
    * its length is greater than 0, and it contains at least one non-whitespace character.
    * @param str the String to check (may be <code>null</code>)
    * @return <code>true</code> if the String is not <code>null</code>, its length is
    * greater than 0, and it does not contain whitespace only
    * @see #hasText(CharSequence)
    */
   public static boolean hasText(String str) {
      return hasText((CharSequence) str);
   }

   /**
    * Check whether the given CharSequence contains any whitespace characters.
    * @param str the CharSequence to check (may be <code>null</code>)
    * @return <code>true</code> if the CharSequence is not empty and
    * contains at least 1 whitespace character
    * @see java.lang.Character#isWhitespace
    */
   public static boolean containsWhitespace(CharSequence str) {
      if (!hasLength(str)) {
         return false;
      }
      int strLen = str.length();
      for (int i = 0; i < strLen; i++) {
         if (Character.isWhitespace(str.charAt(i))) {
            return true;
         }
      }
      return false;
   }

   /**
    * Check whether the given String contains any whitespace characters.
    * @param str the String to check (may be <code>null</code>)
    * @return <code>true</code> if the String is not empty and
    * contains at least 1 whitespace character
    * @see #containsWhitespace(CharSequence)
    */
   public static boolean containsWhitespace(String str) {
      return containsWhitespace((CharSequence) str);
   }

   /**
    * Trim leading and trailing whitespace from the given String.
    * @param str the String to check
    * @return the trimmed String
    * @see java.lang.Character#isWhitespace
    */
   public static String trimWhitespace(String str) {
      if (!hasLength(str)) {
         return str;
      }
      StringBuilder sb = new StringBuilder(str);
      while (sb.length() > 0 && Character.isWhitespace(sb.charAt(0))) {
         sb.deleteCharAt(0);
      }
      while (sb.length() > 0 && Character.isWhitespace(sb.charAt(sb.length() - 1))) {
         sb.deleteCharAt(sb.length() - 1);
      }
      return sb.toString();
   }

   /**
    * Trim <i>all</i> whitespace from the given String:
    * leading, trailing, and inbetween characters.
    * @param str the String to check
    * @return the trimmed String
    * @see java.lang.Character#isWhitespace
    */
   public static String trimAllWhitespace(String str) {
      if (!hasLength(str)) {
         return str;
      }
      StringBuilder sb = new StringBuilder(str);
      int index = 0;
      while (sb.length() > index) {
         if (Character.isWhitespace(sb.charAt(index))) {
            sb.deleteCharAt(index);
         }
         else {
            index++;
         }
      }
      return sb.toString();
   }

   /**
    * Trim leading whitespace from the given String.
    * @param str the String to check
    * @return the trimmed String
    * @see java.lang.Character#isWhitespace
    */
   public static String trimLeadingWhitespace(String str) {
      if (!hasLength(str)) {
         return str;
      }
      StringBuilder sb = new StringBuilder(str);
      while (sb.length() > 0 && Character.isWhitespace(sb.charAt(0))) {
         sb.deleteCharAt(0);
      }
      return sb.toString();
   }

   /**
    * Trim trailing whitespace from the given String.
    * @param str the String to check
    * @return the trimmed String
    * @see java.lang.Character#isWhitespace
    */
   public static String trimTrailingWhitespace(String str) {
      if (!hasLength(str)) {
         return str;
      }
      StringBuilder sb = new StringBuilder(str);
      while (sb.length() > 0 && Character.isWhitespace(sb.charAt(sb.length() - 1))) {
         sb.deleteCharAt(sb.length() - 1);
      }
      return sb.toString();
   }

   /**
    * Trim all occurences of the supplied leading character from the given String.
    * @param str the String to check
    * @param leadingCharacter the leading character to be trimmed
    * @return the trimmed String
    */
   public static String trimLeadingCharacter(String str, char leadingCharacter) {
      if (!hasLength(str)) {
         return str;
      }
      StringBuilder sb = new StringBuilder(str);
      while (sb.length() > 0 && sb.charAt(0) == leadingCharacter) {
         sb.deleteCharAt(0);
      }
      return sb.toString();
   }

   /**
    * Trim all occurences of the supplied trailing character from the given String.
    * @param str the String to check
    * @param trailingCharacter the trailing character to be trimmed
    * @return the trimmed String
    */
   public static String trimTrailingCharacter(String str, char trailingCharacter) {
      if (!hasLength(str)) {
         return str;
      }
      StringBuilder sb = new StringBuilder(str);
      while (sb.length() > 0 && sb.charAt(sb.length() - 1) == trailingCharacter) {
         sb.deleteCharAt(sb.length() - 1);
      }
      return sb.toString();
   }


   /**
    * Test if the given String starts with the specified prefix,
    * ignoring upper/lower case.
    * @param str the String to check
    * @param prefix the prefix to look for
    * @see java.lang.String#startsWith
    */
   public static boolean startsWithIgnoreCase(String str, String prefix) {
      if (str == null || prefix == null) {
         return false;
      }
      if (str.startsWith(prefix)) {
         return true;
      }
      if (str.length() < prefix.length()) {
         return false;
      }
      String lcStr = str.substring(0, prefix.length()).toLowerCase();
      String lcPrefix = prefix.toLowerCase();
      return lcStr.equals(lcPrefix);
   }

   /**
    * Test if the given String ends with the specified suffix,
    * ignoring upper/lower case.
    * @param str the String to check
    * @param suffix the suffix to look for
    * @see java.lang.String#endsWith
    */
   public static boolean endsWithIgnoreCase(String str, String suffix) {
      if (str == null || suffix == null) {
         return false;
      }
      if (str.endsWith(suffix)) {
         return true;
      }
      if (str.length() < suffix.length()) {
         return false;
      }

      String lcStr = str.substring(str.length() - suffix.length()).toLowerCase();
      String lcSuffix = suffix.toLowerCase();
      return lcStr.equals(lcSuffix);
   }

   /**
    * Test whether the given string matches the given substring
    * at the given index.
    * @param str the original string (or StringBuilder)
    * @param index the index in the original string to start matching against
    * @param substring the substring to match at the given index
    */
   public static boolean substringMatch(CharSequence str, int index, CharSequence substring) {
      for (int j = 0; j < substring.length(); j++) {
         int i = index + j;
         if (i >= str.length() || str.charAt(i) != substring.charAt(j)) {
            return false;
         }
      }
      return true;
   }

   /**
    * Count the occurrences of the substring in string s.
    * @param str string to search in. Return 0 if this is null.
    * @param sub string to search for. Return 0 if this is null.
    */
   public static int countOccurrencesOf(String str, String sub) {
      if (str == null || sub == null || str.length() == 0 || sub.length() == 0) {
         return 0;
      }
      int count = 0;
      int pos = 0;
      int idx;
      while ((idx = str.indexOf(sub, pos)) != -1) {
         ++count;
         pos = idx + sub.length();
      }
      return count;
   }

   /**
    * Replace all occurences of a substring within a string with
    * another string.
    * @param inString String to examine
    * @param oldPattern String to replace
    * @param newPattern String to insert
    * @return a String with the replacements
    */
   public static String replace(String inString, String oldPattern, String newPattern) {
      if (!hasLength(inString) || !hasLength(oldPattern) || newPattern == null) {
         return inString;
      }
      StringBuilder sb = new StringBuilder();
      int pos = 0; // our position in the old string
      int index = inString.indexOf(oldPattern);
      // the index of an occurrence we've found, or -1
      int patLen = oldPattern.length();
      while (index >= 0) {
         sb.append(inString.substring(pos, index));
         sb.append(newPattern);
         pos = index + patLen;
         index = inString.indexOf(oldPattern, pos);
      }
      sb.append(inString.substring(pos));
      // remember to append any characters to the right of a match
      return sb.toString();
   }

   /**
    * Delete all occurrences of the given substring.
    * @param inString the original String
    * @param pattern the pattern to delete all occurrences of
    * @return the resulting String
    */
   public static String delete(String inString, String pattern) {
      return replace(inString, pattern, "");
   }

   /**
    * Delete any character in a given String.
    * @param inString the original String
    * @param charsToDelete a set of characters to delete.
    * E.g. "az\n" will delete 'a's, 'z's and new lines.
    * @return the resulting String
    */
   public static String deleteAny(String inString, String charsToDelete) {
      if (!hasLength(inString) || !hasLength(charsToDelete)) {
         return inString;
      }
      StringBuilder sb = new StringBuilder();
      for (int i = 0; i < inString.length(); i++) {
         char c = inString.charAt(i);
         if (charsToDelete.indexOf(c) == -1) {
            sb.append(c);
         }
      }
      return sb.toString();
   }


   //---------------------------------------------------------------------
   // Convenience methods for working with formatted Strings
   //---------------------------------------------------------------------

   /**
    * Quote the given String with single quotes.
    * @param str the input String (e.g. "myString")
    * @return the quoted String (e.g. "'myString'"),
    * or <code>null<code> if the input was <code>null</code>
    */
   public static String quote(String str) {
      return (str != null ? "'" + str + "'" : null);
   }

   /**
    * Turn the given Object into a String with single quotes
    * if it is a String; keeping the Object as-is else.
    * @param obj the input Object (e.g. "myString")
    * @return the quoted String (e.g. "'myString'"),
    * or the input object as-is if not a String
    */
   public static Object quoteIfString(Object obj) {
      return (obj instanceof String ? quote((String) obj) : obj);
   }

   /**
    * Unqualify a string qualified by a '.' dot character. For example,
    * "this.name.is.qualified", returns "qualified".
    * @param qualifiedName the qualified name
    */
   public static String unqualify(String qualifiedName) {
      return unqualify(qualifiedName, '.');
   }

   /**
    * Unqualify a string qualified by a separator character. For example,
    * "this:name:is:qualified" returns "qualified" if using a ':' separator.
    * @param qualifiedName the qualified name
    * @param separator the separator
    */
   public static String unqualify(String qualifiedName, char separator) {
      return qualifiedName.substring(qualifiedName.lastIndexOf(separator) + 1);
   }

   /**
    * Capitalize a <code>String</code>, changing the first letter to
    * upper case as per {@link Character#toUpperCase(char)}.
    * No other letters are changed.
    * @param str the String to capitalize, may be <code>null</code>
    * @return the capitalized String, <code>null</code> if null
    */
   public static String capitalize(String str) {
      return changeFirstCharacterCase(str, true);
   }

   /**
    * Uncapitalize a <code>String</code>, changing the first letter to
    * lower case as per {@link Character#toLowerCase(char)}.
    * No other letters are changed.
    * @param str the String to uncapitalize, may be <code>null</code>
    * @return the uncapitalized String, <code>null</code> if null
    */
   public static String uncapitalize(String str) {
      return changeFirstCharacterCase(str, false);
   }

   private static String changeFirstCharacterCase(String str, boolean capitalize) {
      if (str == null || str.length() == 0) {
         return str;
      }
      StringBuilder sb = new StringBuilder(str.length());
      if (capitalize) {
         sb.append(Character.toUpperCase(str.charAt(0)));
      }
      else {
         sb.append(Character.toLowerCase(str.charAt(0)));
      }
      sb.append(str.substring(1));
      return sb.toString();
   }

   /**
    * Extract the filename from the given path,
    * e.g. "mypath/myfile.txt" -> "myfile.txt".
    * @param path the file path (may be <code>null</code>)
    * @return the extracted filename, or <code>null</code> if none
    */
   public static String getFilename(String path) {
      if (path == null) {
         return null;
      }
      int separatorIndex = path.lastIndexOf(FOLDER_SEPARATOR);
      return (separatorIndex != -1 ? path.substring(separatorIndex + 1) : path);
   }

   /**
    * Extract the filename extension from the given path,
    * e.g. "mypath/myfile.txt" -> "txt".
    * @param path the file path (may be <code>null</code>)
    * @return the extracted filename extension, or <code>null</code> if none
    */
   public static String getFilenameExtension(String path) {
      if (path == null) {
         return null;
      }
      int sepIndex = path.lastIndexOf(EXTENSION_SEPARATOR);
      return (sepIndex != -1 ? path.substring(sepIndex + 1) : null);
   }

   /**
    * Strip the filename extension from the given path,
    * e.g. "mypath/myfile.txt" -> "mypath/myfile".
    * @param path the file path (may be <code>null</code>)
    * @return the path with stripped filename extension,
    * or <code>null</code> if none
    */
   public static String stripFilenameExtension(String path) {
      if (path == null) {
         return null;
      }
      int sepIndex = path.lastIndexOf(EXTENSION_SEPARATOR);
      return (sepIndex != -1 ? path.substring(0, sepIndex) : path);
   }

   /**
    * Apply the given relative path to the given path,
    * assuming standard Java folder separation (i.e. "/" separators).
    * @param path the path to start from (usually a full file path)
    * @param relativePath the relative path to apply
    * (relative to the full file path above)
    * @return the full file path that results from applying the relative path
    */
   public static String applyRelativePath(String path, String relativePath) {
      int separatorIndex = path.lastIndexOf(FOLDER_SEPARATOR);
      if (separatorIndex != -1) {
         String newPath = path.substring(0, separatorIndex);
         if (!relativePath.startsWith(FOLDER_SEPARATOR)) {
            newPath += FOLDER_SEPARATOR;
         }
         return newPath + relativePath;
      }
      else {
         return relativePath;
      }
   }

   /**
    * Normalize the path by suppressing sequences like "path/.." and
    * inner simple dots.
    * <p>The result is convenient for path comparison. For other uses,
    * notice that Windows separators ("\") are replaced by simple slashes.
    * @param path the original path
    * @return the normalized path
    */
   public static String cleanPath(String path) {
      if (path == null) {
         return null;
      }
      String pathToUse = replace(path, WINDOWS_FOLDER_SEPARATOR, FOLDER_SEPARATOR);

      // Strip prefix from path to analyze, to not treat it as part of the
      // first path element. This is necessary to correctly parse paths like
      // "file:core/../core/io/Resource.class", where the ".." should just
      // strip the first "core" directory while keeping the "file:" prefix.
      int prefixIndex = pathToUse.indexOf(":");
      String prefix = "";
      if (prefixIndex != -1) {
         prefix = pathToUse.substring(0, prefixIndex + 1);
         pathToUse = pathToUse.substring(prefixIndex + 1);
      }
      if (pathToUse.startsWith(FOLDER_SEPARATOR)) {
         prefix = prefix + FOLDER_SEPARATOR;
         pathToUse = pathToUse.substring(1);
      }

      String[] pathArray = delimitedListToStringArray(pathToUse, FOLDER_SEPARATOR);
      List<String> pathElements = new LinkedList<String>();
      int tops = 0;

      for (int i = pathArray.length - 1; i >= 0; i--) {
         String element = pathArray[i];
         if (CURRENT_PATH.equals(element)) {
            // Points to current directory - drop it.
         }
         else if (TOP_PATH.equals(element)) {
            // Registering top path found.
            tops++;
         }
         else {
            if (tops > 0) {
               // Merging path element with element corresponding to top path.
               tops--;
            }
            else {
               // Normal path element found.
               pathElements.add(0, element);
            }
         }
      }

      // Remaining top paths need to be retained.
      for (int i = 0; i < tops; i++) {
         pathElements.add(0, TOP_PATH);
      }

      return prefix + collectionToDelimitedString(pathElements, FOLDER_SEPARATOR);
   }

   /**
    * Compare two paths after normalization of them.
    * @param path1 first path for comparison
    * @param path2 second path for comparison
    * @return whether the two paths are equivalent after normalization
    */
   public static boolean pathEquals(String path1, String path2) {
      return cleanPath(path1).equals(cleanPath(path2));
   }

   /**
    * Parse the given <code>localeString</code> into a {@link Locale}.
    * <p>This is the inverse operation of {@link Locale#toString Locale's toString}.
    * @param localeString the locale string, following <code>Locale's</code>
    * <code>toString()</code> format ("en", "en_UK", etc);
    * also accepts spaces as separators, as an alternative to underscores
    * @return a corresponding <code>Locale</code> instance
    */
   public static Locale parseLocaleString(String localeString) {
      String[] parts = tokenizeToStringArray(localeString, "_ ", false, false);
      String language = (parts.length > 0 ? parts[0] : "");
      String country = (parts.length > 1 ? parts[1] : "");
      String variant = "";
      if (parts.length >= 2) {
         // There is definitely a variant, and it is everything after the country
         // code sans the separator between the country code and the variant.
         int endIndexOfCountryCode = localeString.indexOf(country) + country.length();
         // Strip off any leading '_' and whitespace, what's left is the variant.
         variant = trimLeadingWhitespace(localeString.substring(endIndexOfCountryCode));
         if (variant.startsWith("_")) {
            variant = trimLeadingCharacter(variant, '_');
         }
      }
      return (language.length() > 0 ? new Locale(language, country, variant) : null);
   }

   /**
    * Determine the RFC 3066 compliant language tag,
    * as used for the HTTP "Accept-Language" header.
    * @param locale the Locale to transform to a language tag
    * @return the RFC 3066 compliant language tag as String
    */
   public static String toLanguageTag(Locale locale) {
      return locale.getLanguage() + (hasText(locale.getCountry()) ? "-" + locale.getCountry() : "");
   }


   //---------------------------------------------------------------------
   // Convenience methods for working with String arrays
   //---------------------------------------------------------------------

   /**
    * Append the given String to the given String array, returning a new array
    * consisting of the input array contents plus the given String.
    * @param array the array to append to (can be <code>null</code>)
    * @param str the String to append
    * @return the new array (never <code>null</code>)
    */
   public static String[] addStringToArray(String[] array, String str) {
      if (ObjectUtils.isEmpty(array)) {
         return new String[] {str};
      }
      String[] newArr = new String[array.length + 1];
      System.arraycopy(array, 0, newArr, 0, array.length);
      newArr[array.length] = str;
      return newArr;
   }

   /**
    * Concatenate the given String arrays into one,
    * with overlapping array elements included twice.
    * <p>The order of elements in the original arrays is preserved.
    * @param array1 the first array (can be <code>null</code>)
    * @param array2 the second array (can be <code>null</code>)
    * @return the new array (<code>null</code> if both given arrays were <code>null</code>)
    */
   public static String[] concatenateStringArrays(String[] array1, String[] array2) {
      if (ObjectUtils.isEmpty(array1)) {
         return array2;
      }
      if (ObjectUtils.isEmpty(array2)) {
         return array1;
      }
      String[] newArr = new String[array1.length + array2.length];
      System.arraycopy(array1, 0, newArr, 0, array1.length);
      System.arraycopy(array2, 0, newArr, array1.length, array2.length);
      return newArr;
   }

   /**
    * Merge the given String arrays into one, with overlapping
    * array elements only included once.
    * <p>The order of elements in the original arrays is preserved
    * (with the exception of overlapping elements, which are only
    * included on their first occurence).
    * @param array1 the first array (can be <code>null</code>)
    * @param array2 the second array (can be <code>null</code>)
    * @return the new array (<code>null</code> if both given arrays were <code>null</code>)
    */
   public static String[] mergeStringArrays(String[] array1, String[] array2) {
      if (ObjectUtils.isEmpty(array1)) {
         return array2;
      }
      if (ObjectUtils.isEmpty(array2)) {
         return array1;
      }
      List<String> result = new ArrayList<String>();
      result.addAll(Arrays.asList(array1));
      for (String str : array2) {
         if (!result.contains(str)) {
            result.add(str);
         }
      }
      return toStringArray(result);
   }

   /**
    * Turn given source String array into sorted array.
    * @param array the source array
    * @return the sorted array (never <code>null</code>)
    */
   public static String[] sortStringArray(String[] array) {
      if (ObjectUtils.isEmpty(array)) {
         return new String[0];
      }
      Arrays.sort(array);
      return array;
   }

   /**
    * Copy the given Collection into a String array.
    * The Collection must contain String elements only.
    * @param collection the Collection to copy
    * @return the String array (<code>null</code> if the passed-in
    * Collection was <code>null</code>)
    */
   public static String[] toStringArray(Collection<String> collection) {
      if (collection == null) {
         return null;
      }
      return collection.toArray(new String[collection.size()]);
   }

   /**
    * Copy the given Enumeration into a String array.
    * The Enumeration must contain String elements only.
    * @param enumeration the Enumeration to copy
    * @return the String array (<code>null</code> if the passed-in
    * Enumeration was <code>null</code>)
    */
   public static String[] toStringArray(Enumeration<String> enumeration) {
      if (enumeration == null) {
         return null;
      }
      List<String> list = Collections.list(enumeration);
      return list.toArray(new String[list.size()]);
   }

   /**
    * Trim the elements of the given String array,
    * calling <code>String.trim()</code> on each of them.
    * @param array the original String array
    * @return the resulting array (of the same size) with trimmed elements
    */
   public static String[] trimArrayElements(String[] array) {
      if (ObjectUtils.isEmpty(array)) {
         return new String[0];
      }
      String[] result = new String[array.length];
      for (int i = 0; i < array.length; i++) {
         String element = array[i];
         result[i] = (element != null ? element.trim() : null);
      }
      return result;
   }

   /**
    * Remove duplicate Strings from the given array.
    * Also sorts the array, as it uses a TreeSet.
    * @param array the String array
    * @return an array without duplicates, in natural sort order
    */
   public static String[] removeDuplicateStrings(String[] array) {
      if (ObjectUtils.isEmpty(array)) {
         return array;
      }
      Set<String> set = new TreeSet<String>();
      for (String element : array) {
         set.add(element);
      }
      return toStringArray(set);
   }

   /**
    * Split a String at the first occurrence of the delimiter.
    * Does not include the delimiter in the result.
    * @param toSplit the string to split
    * @param delimiter to split the string up with
    * @return a two element array with index 0 being before the delimiter, and
    * index 1 being after the delimiter (neither element includes the delimiter);
    * or <code>null</code> if the delimiter wasn't found in the given input String
    */
   public static String[] split(String toSplit, String delimiter) {
      if (!hasLength(toSplit) || !hasLength(delimiter)) {
         return null;
      }
      int offset = toSplit.indexOf(delimiter);
      if (offset < 0) {
         return null;
      }
      String beforeDelimiter = toSplit.substring(0, offset);
      String afterDelimiter = toSplit.substring(offset + delimiter.length());
      return new String[] {beforeDelimiter, afterDelimiter};
   }

   /**
    * Take an array Strings and split each element based on the given delimiter.
    * A <code>Properties</code> instance is then generated, with the left of the
    * delimiter providing the key, and the right of the delimiter providing the value.
    * <p>Will trim both the key and value before adding them to the
    * <code>Properties</code> instance.
    * @param array the array to process
    * @param delimiter to split each element using (typically the equals symbol)
    * @return a <code>Properties</code> instance representing the array contents,
    * or <code>null</code> if the array to process was null or empty
    */
   public static Properties splitArrayElementsIntoProperties(String[] array, String delimiter) {
      return splitArrayElementsIntoProperties(array, delimiter, null);
   }

   /**
    * Take an array Strings and split each element based on the given delimiter.
    * A <code>Properties</code> instance is then generated, with the left of the
    * delimiter providing the key, and the right of the delimiter providing the value.
    * <p>Will trim both the key and value before adding them to the
    * <code>Properties</code> instance.
    * @param array the array to process
    * @param delimiter to split each element using (typically the equals symbol)
    * @param charsToDelete one or more characters to remove from each element
    * prior to attempting the split operation (typically the quotation mark
    * symbol), or <code>null</code> if no removal should occur
    * @return a <code>Properties</code> instance representing the array contents,
    * or <code>null</code> if the array to process was <code>null</code> or empty
    */
   public static Properties splitArrayElementsIntoProperties(
         String[] array, String delimiter, String charsToDelete) {

      if (ObjectUtils.isEmpty(array)) {
         return null;
      }
      Properties result = new Properties();
      for (String element : array) {
         if (charsToDelete != null) {
            element = deleteAny(element, charsToDelete);
         }
         String[] splittedElement = split(element, delimiter);
         if (splittedElement == null) {
            continue;
         }
         result.setProperty(splittedElement[0].trim(), splittedElement[1].trim());
      }
      return result;
   }

   /**
    * Tokenize the given String into a String array via a StringTokenizer.
    * Trims tokens and omits empty tokens.
    * <p>The given delimiters string is supposed to consist of any number of
    * delimiter characters. Each of those characters can be used to separate
    * tokens. A delimiter is always a single character; for multi-character
    * delimiters, consider using <code>delimitedListToStringArray</code>
    * @param str the String to tokenize
    * @param delimiters the delimiter characters, assembled as String
    * (each of those characters is individually considered as delimiter).
    * @return an array of the tokens
    * @see java.util.StringTokenizer
    * @see java.lang.String#trim()
    * @see #delimitedListToStringArray
    */
   public static String[] tokenizeToStringArray(String str, String delimiters) {
      return tokenizeToStringArray(str, delimiters, true, true);
   }

   /**
    * Tokenize the given String into a String array via a StringTokenizer.
    * <p>The given delimiters string is supposed to consist of any number of
    * delimiter characters. Each of those characters can be used to separate
    * tokens. A delimiter is always a single character; for multi-character
    * delimiters, consider using <code>delimitedListToStringArray</code>
    * @param str the String to tokenize
    * @param delimiters the delimiter characters, assembled as String
    * (each of those characters is individually considered as delimiter)
    * @param trimTokens trim the tokens via String's <code>trim</code>
    * @param ignoreEmptyTokens omit empty tokens from the result array
    * (only applies to tokens that are empty after trimming; StringTokenizer
    * will not consider subsequent delimiters as token in the first place).
    * @return an array of the tokens (<code>null</code> if the input String
    * was <code>null</code>)
    * @see java.util.StringTokenizer
    * @see java.lang.String#trim()
    * @see #delimitedListToStringArray
    */
   public static String[] tokenizeToStringArray(
         String str, String delimiters, boolean trimTokens, boolean ignoreEmptyTokens) {

      if (str == null) {
         return null;
      }
      StringTokenizer st = new StringTokenizer(str, delimiters);
      List<String> tokens = new ArrayList<String>();
      while (st.hasMoreTokens()) {
         String token = st.nextToken();
         if (trimTokens) {
            token = token.trim();
         }
         if (!ignoreEmptyTokens || token.length() > 0) {
            tokens.add(token);
         }
      }
      return toStringArray(tokens);
   }

   /**
    * Take a String which is a delimited list and convert it to a String array.
    * <p>A single delimiter can consists of more than one character: It will still
    * be considered as single delimiter string, rather than as bunch of potential
    * delimiter characters - in contrast to <code>tokenizeToStringArray</code>.
    * @param str the input String
    * @param delimiter the delimiter between elements (this is a single delimiter,
    * rather than a bunch individual delimiter characters)
    * @return an array of the tokens in the list
    * @see #tokenizeToStringArray
    */
   public static String[] delimitedListToStringArray(String str, String delimiter) {
      return delimitedListToStringArray(str, delimiter, null);
   }

   /**
    * Take a String which is a delimited list and convert it to a String array.
    * <p>A single delimiter can consists of more than one character: It will still
    * be considered as single delimiter string, rather than as bunch of potential
    * delimiter characters - in contrast to <code>tokenizeToStringArray</code>.
    * @param str the input String
    * @param delimiter the delimiter between elements (this is a single delimiter,
    * rather than a bunch individual delimiter characters)
    * @param charsToDelete a set of characters to delete. Useful for deleting unwanted
    * line breaks: e.g. "\r\n\f" will delete all new lines and line feeds in a String.
    * @return an array of the tokens in the list
    * @see #tokenizeToStringArray
    */
   public static String[] delimitedListToStringArray(String str, String delimiter, String charsToDelete) {
      if (str == null) {
         return new String[0];
      }
      if (delimiter == null) {
         return new String[] {str};
      }
      List<String> result = new ArrayList<String>();
      if ("".equals(delimiter)) {
         for (int i = 0; i < str.length(); i++) {
            result.add(deleteAny(str.substring(i, i + 1), charsToDelete));
         }
      }
      else {
         int pos = 0;
         int delPos;
         while ((delPos = str.indexOf(delimiter, pos)) != -1) {
            result.add(deleteAny(str.substring(pos, delPos), charsToDelete));
            pos = delPos + delimiter.length();
         }
         if (str.length() > 0 && pos <= str.length()) {
            // Add rest of String, but not in case of empty input.
            result.add(deleteAny(str.substring(pos), charsToDelete));
         }
      }
      return toStringArray(result);
   }

   /**
    * Convert a CSV list into an array of Strings.
    * @param str the input String
    * @return an array of Strings, or the empty array in case of empty input
    */
   public static String[] commaDelimitedListToStringArray(String str) {
      return delimitedListToStringArray(str, ",");
   }

   /**
    * Convenience method to convert a CSV string list to a set.
    * Note that this will suppress duplicates.
    * @param str the input String
    * @return a Set of String entries in the list
    */
   public static Set<String> commaDelimitedListToSet(String str) {
      Set<String> set = new TreeSet<String>();
      String[] tokens = commaDelimitedListToStringArray(str);
      for (String token : tokens) {
         set.add(token);
      }
      return set;
   }

   /**
    * Convenience method to return a Collection as a delimited (e.g. CSV)
    * String. E.g. useful for <code>toString()</code> implementations.
    * @param coll the Collection to display
    * @param delim the delimiter to use (probably a ",")
    * @param prefix the String to start each element with
    * @param suffix the String to end each element with
    * @return the delimited String
    */
   public static String collectionToDelimitedString(Collection coll, String delim, String prefix, String suffix) {
      if (CollectionUtils.isEmpty(coll)) {
         return "";
      }
      StringBuilder sb = new StringBuilder();
      Iterator it = coll.iterator();
      while (it.hasNext()) {
         sb.append(prefix).append(it.next()).append(suffix);
         if (it.hasNext()) {
            sb.append(delim);
         }
      }
      return sb.toString();
   }

   /**
    * Convenience method to return a Collection as a delimited (e.g. CSV)
    * String. E.g. useful for <code>toString()</code> implementations.
    * @param coll the Collection to display
    * @param delim the delimiter to use (probably a ",")
    * @return the delimited String
    */
   public static String collectionToDelimitedString(Collection coll, String delim) {
      return collectionToDelimitedString(coll, delim, "", "");
   }

   /**
    * Convenience method to return a Collection as a CSV String.
    * E.g. useful for <code>toString()</code> implementations.
    * @param coll the Collection to display
    * @return the delimited String
    */
   public static String collectionToCommaDelimitedString(Collection coll) {
      return collectionToDelimitedString(coll, ",");
   }

   /**
    * Convenience method to return a String array as a delimited (e.g. CSV)
    * String. E.g. useful for <code>toString()</code> implementations.
    * @param arr the array to display
    * @param delim the delimiter to use (probably a ",")
    * @return the delimited String
    */
   public static String arrayToDelimitedString(Object[] arr, String delim) {
      if (ObjectUtils.isEmpty(arr)) {
         return "";
      }
      if (arr.length == 1) {
         return ObjectUtils.nullSafeToString(arr[0]);
      }
      StringBuilder sb = new StringBuilder();
      for (int i = 0; i < arr.length; i++) {
         if (i > 0) {
            sb.append(delim);
         }
         sb.append(arr[i]);
      }
      return sb.toString();
   }

   /**
    * Convenience method to return a String array as a CSV String.
    * E.g. useful for <code>toString()</code> implementations.
    * @param arr the array to display
    * @return the delimited String
    */
   public static String arrayToCommaDelimitedString(Object[] arr) {
      return arrayToDelimitedString(arr, ",");
   }

}
